In the past it has been known to provide an arch adjustment in a walking shoe by adjusting the upward arch of a flexible insole plate. Examples are U.S. Pat No. 899,367 (Winchell); U.S. Pat. No. 1,242,317 (Boyajin); U.S. Pat. No. 1,523,353 (Winchell); and U.S. Pat. No. 2,295,364 (Skorepa). In the later of the two Winchell patents, a turnbuckle is turned at the center to cause beveled nuts to travel along a beveled transverse track to vary the upward arch of a flexible insole member engaged by the nuts on its underside. In the earlier Winchell patent, a lateral screw is turned in a fixed nut to force a bottom brace to flex a sole plate with which it is slidably connected by end tongues passing through slots. In both Winchell patents the adjusting screws are within the shoe. The Boyajin patent has a flexible inside plate anchored at its forward end and adjusted longitudinally to bend the plate upwardly by a screw operating in a cavity hidden at the top of the shoe heel. The Skorepa patent discloses a similar device in which access to the adjusting screw is had by removing an end plug in the heel. None of these prior art arch adjusting mechanisms is considered suitable or practical for use with a water ski boat.
A water ski boot needs to be adapted to be used with a right or left foot. Hence, if there is to be an arch support for the foot in the boot, it must be not only adjustable in height for comfort by various skiers, it should be adjustable such as to provide an arch support at either side depending upon which foot the water ski is to be mounted. Furthermore, there should be easy access to the adjusting mechanism.